1. Field of the Invention
The present invention relates to a machine tool which machines a workpiece by moving a tool mounted on a spindle and the workpiece relative to each other and, in particular, to a machine tool that has an excellent chip discharge capability.
2. Description of the Related Art
In the field of machine tools, effectively discharging to the outside of the machine tool large amounts of cutting chips produced when machining the workpiece with the tool is very important. For example, Japanese Unexamined Utility Model Publication No. 58-93437 (more particularly, FIG. 3 thereof) proposes a structure which drops cutting chips, along an angled cover which covers a guide means and a feed screw in a workpiece table and which is inclined downward from the center toward left and right, into troughs arranged in a bed on both the right and left sides of the workpiece table, to collect the cutting chips in the right and left troughs. Also, Japanese Unexamined Patent Publication No. 9-309042 (more particularly, FIG. 1 thereof) proposes a structure which provides a concave trough, extending parallel to the direction of movement of a table, in the center of a bed, and which drops cutting chips along a trough-shaped cover which is inclined downward from the left and right sides toward the center to collect the chips in the concave trough. Further, Japanese Unexamined Utility Model Publication No. 2-35634 proposes a structure which provides a chip collection port, arranged on the upper surface of a bed, for dropping cutting chips into a chip conveyor which extends through the bed.
In addition, Japanese Unexamined Utility Model Publication No. 60-175541 proposes a structure which provides a chip collection channel, on both the far and near sides of a table, extending parallel to the direction of movement of the table and having a screw conveyor arranged therein; Japanese Unexamined Patent Publication No. 61-103754 proposes a structure which provides a chip collection channel, between a table and a column, extending in a direction perpendicular to the direction of movement of the table and having a lift conveyor arranged therein, and a structure in which inclined surfaces are formed on a bed surrounding a table, for guiding cutting chips and a cutting fluid to a screw conveyor arranged in a chip collection channel; and Japanese Unexamined Patent Publication No. 8-57739 proposes a structure which provides a chip collection channel, between a table and a column, extending parallel to the direction of movement of the table and having a screw conveyor arranged therein.
However, the above-mentioned conventional structures encounter the following problems.
In the structure disclosed in Japanese Unexamined Utility Model Publication No. 58-93437, if applied to an increased size of the machine tool, the distance between the troughs provided on both sides also increases, and therefore there is the problem that the angle of inclination of the angled cover cannot be steep so that chips are likely to accumulate on the surface of the inclined cover. In the structure disclosed in Japanese Unexamined Patent Publication No. 9-309042, the table feed screw is located in the center of the bed, i.e. above the concave trough and therefore takes much space above the trough to make it difficult for the chips to fall into the trough. In addition, as the concave trough is arranged parallel to the direction of movement of the table, the cutting chips are discharged from the front or rear portion of the machine to the outside. This raises the problem of the machine taking up a large area for installation. Also, because a concave channel for mounting the concave trough component therein is formed in the bed, the rigidity of the bed is reduced. There is also the problem that, as the size of the machine increases, the angle of inclination of the angled cover decreases to be gentler so that chips accumulate on the cover. In the structure disclosed in Japanese Unexamined Patent Publication No. 8-57739, there is the problem that, as the chip collection channel is provided only between the table and the column, the cutting chips and cutting fluid that scatters towards the front of the table cannot be collected. Further, in the structures wherein the cutting chips and cutting fluid fall directly onto the bed as disclosed in Japanese Unexamined Utility Model Publication No. 60-175541, Japanese Unexamined Patent Publication No. 61-103754, and Japanese Unexamined Utility Model Publication No. 2-35634, there is the problem that high temperature cutting chips and cutting fluid may cause heat deformation in the bed and result in the reduced precision of the machine tool.
The object of the present invention is to provide a machine tool which, while improving the capability of discharging and collecting the cutting chips generated by machining the workpiece, does not increase the size and complexity of the structure of the machine tool and does not generate heat deformation of the bed due to high temperature cutting chips and cutting fluid.
The present invention, in view of the above object, provides a machine tool which is provided with a bed having troughs extending in a direction perpendicular to the direction of the movement of the table, thereby to collect the cutting chips, falling from the table down to its surrounding, in the troughs through a plurality of chutes, and to discharge the cutting chips collected in the troughs to the outside.
Specifically, the present invention provides a machine tool for machining a workpiece by moving the workpiece and a tool relative to each other, which includes a bed serving as a base; a spindle head for rotatably supporting a spindle having the tool mounted thereon; a table for the workpiece to be mounted thereon, the table moving along guide means disposed on the upper surface of the bed; table feed means for moving the table along the guide means; an inclined cover for covering the guide means and the table feed means of the table and causing cutting chips generated by machining the workpiece to fall downwards; a plurality of chutes having openings for collecting the cutting chips below the upper surface of the table; a trough for receiving the cutting chips collected by the plurality of chutes, the trough extending through the bed below the table and in a direction substantially perpendicular to the direction of the movement of the table; and chip discharge means for discharging the cutting chips received by the troughs to the outside, the chip discharge means disposed in the trough.
Preferably, the above machine tool includes a plurality of the troughs, and the chip discharge means are disposed in each of the plurality of the troughs.
Preferably, the table moves along two spaced guide means, and the plurality of chutes are composed of a central chute arranged between the guide means of the table, and left and right chutes arranged on either outer side of the guide means of the table.
Further, the plurality of chutes and troughs are preferably spaced apart from the bed.
In the machine tool according to the present invention, the cutting chips and cutting fluid falling down from the table are led into and collected in troughs extending through the bed, through the plurality of chutes arranged so as to cover the surface surrounding the table below the upper surface of the table. Therefore, the cutting chips and cutting fluid can be prevented from scattering around the table and falling down on the bed to generate heat deformation in the bed. Also, because the troughs and chutes are spaced apart from the bed and the cutting chips and cutting fluid are discharged to the outside through the chip discharge means, the high temperature cutting chips and fluid collected in the trough do not generate heat deformation in the bed, as in the prior art, where the high temperature cutting chips and fluid are collected directly in the bed. Further, since the troughs and the chip discharge means are arranged so that the longitudinal direction thereof is perpendicular to the direction of the movement of the bed, the size of the machine tool in the front to rear direction is not increased.
When the machine tool includes a plurality of troughs and the chip discharge means disposed in each of the troughs, the cutting chips and cutting fluid can be more efficiently discharged to the outside of the machine tool. In addition, if the plurality of chutes are disposed in the center and in the right and left side thereof, the capability of collecting the cutting chips can be improved.
It should be noted that a tool charger, etc., are typically arranged by the side of the machine tool, and that if a chip recovery means for recovering the cutting chips and cutting fluid discharged to the side of the bed is arranged under the tool changer, the size of the machine tool in the lateral direction is not increased either.
Also, when the table feed means and the guide means are covered by the cover means, the cutting chips falling from the table can be prevented from attaching to and becoming caught up in the table feed means and the guide means.
Further, the plurality of chutes are formed with the opening inclined downward toward the troughs and the cutting chips do not accumulate on the inclined covers even if the size of the machine is increased. If the troughs are installed using the cast hole formed in the bed by casting, the rigidity of the bed is not reduced.